Storybook: Much higher CPU usage when moving from 5.1.X to 5.2.X on idle storybook

[cherouvim]

I have a create-react-app (all packages to latest version) with 20-40 stories. When npm run storybook has finished and is simply running to monitor file changes, process node on 5.1.X idles at 2.5% but on 5.2.X idles at 30%.

System:

  System:
    OS: Linux 4.4 Ubuntu 16.04.5 LTS (Xenial Xerus)
    CPU: (2) x64 AMD FX(tm)-6300 Six-Core Processor
  Binaries:
    Node: 10.15.3 - /usr/bin/node
    Yarn: 1.15.2 - /usr/bin/yarn
    npm: 6.11.2 - /usr/bin/npm
  npmPackages:
    @storybook/addon-actions: 5.1.x => 5.1.11
    @storybook/addon-centered: 5.1.x => 5.1.11
    @storybook/addon-knobs: 5.1.x => 5.1.11
    @storybook/addons: 5.1.x => 5.1.11
    @storybook/react: 5.1.x => 5.1.11
  npmGlobalPackages:
    @storybook/cli: 4.0.9

[cherouvim]

I confirm this on Windows as well.

[shilman]

Thanks @cherouvim. I saw this in Storybook's official-storybook example and it was bothering me, but I couldn't repro it in a standalone project. Do you have a repro you can share?

[cherouvim]

I've created a reduced repro where I've also removed the addons just to make it simpler.

Currently on my windows machine, the node process when npm install & npm run storybook has completed and is idle:

• this has 0% CPU: 8529-repro-5.1.11.zip
• this has 40% CPU: 8529-repro-5.2.5.zip

[cherouvim]

Regarding the linked issue https://github.com/storybookjs/telejson/issues/26 note that I started Storybook 5.2.5 in a vanilla Ubuntu 18 VM and watch -c "netstat | fgrep tcp" didn't show any signs that storybook connected anywhere while starting up or while running (idling at 30%).

[shilman]

Thanks for checking @cherouvim. I figured that scenario is highly unlikely, but wanted to raise the concern just in case!

[cherouvim]

In case it helps, I've identified that the high CPU issue is introduced when moving from 5.1.11 to 5.2.0.

[shilman]

@cherouvim any interest in bisecting on the 5.2 alphas/betas to see exactly where this got introduced? it would help tremendously!

[cherouvim]

Will do and let you know ASAP.

[cherouvim]

I tested releases in the following order and found that the CPU issue must have been introduced in 5.2.0-alpha.36:

• :-1: 5.2.0-beta.6
• :-1: 5.2.0-beta.0
• :+1: 5.2.0-alpha.23
• :-1: 5.2.0-alpha.37
• :+1: 5.2.0-alpha.30
• :+1: 5.2.0-alpha.33
• :+1: 5.2.0-alpha.35
• :-1: 5.2.0-alpha.36

[shilman]

@cherouvim you are a hero 🥇

@ndelangen how much do you want to bet it's this change: https://github.com/storybookjs/storybook/pull/6265

UPDATE: confirmed in official-storybook

[shilman]

@cherouvim Reverted & released as 5.3.0-alpha.35. Can you upgrade and confirm this fixes the problem on your end? If so I'll patch this out to 5.2.x!

[shilman]

Zoinks!! I just released https://github.com/storybookjs/storybook/releases/tag/v5.3.0-alpha.35 containing PR #8657 that references this issue. Upgrade today to try it out!

You can find this prerelease on the @next NPM tag.

Closing this issue. Please re-open if you think there's still more to do.

[cherouvim]

I confirm that 5.3.0-alpha.35 solves the issue. Thanks.

[shilman]

@cherouvim Great work on tracking it down. Much appreciated!!!

[ndelangen]

You people absolutely 100% ROCK, @cherouvim You deserve a freaking medal 🎖

[cherouvim]

I'm glad I helped. The medal goes to my slow workstation which allowed me to spot this issue in the first place :)

[shilman]

Great Caesar's ghost!! I just released https://github.com/storybookjs/storybook/releases/tag/v5.2.6 containing PR #8657 that references this issue. Upgrade today to try it out!